Field of the Invention
The invention relates to a three-dimensional (3D) printer, particularly to a three-dimensional printer which uniformly spreads material powder to sinter a powder layer, and laminates sintered layers to form a molded object.
Description of Related Art
In powder sintering laminate molding method by a laser beam, material powder is uniformly spread on a table to form a powder layer. A laser beam is irradiated on a predetermined portion of the powder layer to sinter the predetermined portion, thereby forming a sintered layer. The material powder is uniformly spread on this sintered layer to form a new powder layer. A laser beam is irradiated on the new powder layer to sinter the new powder layer, thereby forming a new sintered layer joined to the lower sintered layer. Then, by repeating these processes, a plurality of sintered layers are laminated to form a desired three-dimensional molded object composed of an integrated sintered body.
Herein, a three-dimensional printer is well-known which moves a recoater head on a table in a horizontal uniaxial direction to supply material powder onto the table, and levels the supplied material powder to a uniform thickness by a blade attached to the recoater head while applying a predetermined pressure to the material powder, so as to form a powder layer having a predetermined thickness. As shown in Patent Document 1, a plate-like blade made of metal and having rigidity is generally used. Hereinafter, such material powder layer forming operation is referred to as recoating.
In addition, when the laser beam is irradiated to sinter the powder layer, spark particles scatter, and spark particles may adhere to a surface of the sintered layer to form a projected abnormal sintered portion. If the abnormal sintered portion is formed higher than an upper end surface of the material powder layer, during recoating, the blade sometimes collides with the abnormal sintered portion. As shown in Patent Document 2, a three-dimensional printer is well-known in which when the blade collides with the abnormal sintered portion, the abnormal sintered portion is removed by a cutting tool.